My mother has been on calan sr and wants to switch to the generic. The pharmacist gave her verapamil er. Are er (exended release) and sr (sustained release) equivalent? Shoule she have received verapamil sr? ## Yes, they are the same, though the Verapamil is a generic. The FDA lists its typical side effects as possibly including nausea, dizziness, headache, increased urination, and hypotension. How is she doing? Is she on any other medications?